Purchase this article with an account.
Liming Li, Yiliang Lu, Yan Yan, Yao Chen, Xinyu Chai, Qiushi Ren; Localized Visuotopic Spatial Stimulation of the Penetrative Optic Nerve Visual Prosthesis. Invest. Ophthalmol. Vis. Sci. 2012;53(14):287.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
The purpose of this study is to develop a method of locating the penetrating electrodes inserted into the optic nerve (ON) in the visual field, and further to investigate the spatial properties of electrically evoked potentials (EEPs) elicited by ON stimulation and that of visual evoked potentials (VEPs) elicited by local visual stimulation.
Craniotomy was performed to expose the ON and visual cortex of the cat. Five linearly configured 100KΩ platinum-iridium wire electrodes insulated by Teflon with inter-electrode spacing of 0.15 mm were inserted into the ON ~2 mm posterior to eyeball for both recording and stimulation. The cortical responses in V1 were recorded epidurally by a 5 x 6 silver-ball electrode array in both hemispheres. Spare noise method was established to map visuotopic positions of both ON and V1 electrodes. Local flashing spot stimulation with various luminance and diameters was applied in the visual field corresponding to that of ON electrodes. Spatial properties of EEPs elicited by ON stimulation and VEPs elicited by local visual stimulation were investigated.
The visuotopic positions of ON and V1 electrodes could be mapped by sparse noise method. The maximal EEP response site in V1 visuotopic map has a good correspondence with the ON stimulating electrode site in visual field. The positions of maximal EEP response changed visuotopically when the stimulating electrodes were inserted in various depth and positions of the ON. The stimulating threshold was 3.9 ± 1.5 µA and 321 ± 123 µC/cm2. The spatial spread of EEPs to ON stimulation at 1 to 5 times of current threshold ranged from 2.4 to 4.9 mm, which was comparable to that of VEPs to local visual stimulation at the same visual field with spot radius from 1 to 5.2 degree.
The positions of ON electrodes in the visual field could be mapped by sparse noise method through in-vivo ON recording in cats. Localized visuotopic spatial stimulation could be achieved by penetrating electrodes in various depths and positions of the ON.
This PDF is available to Subscribers Only